The present invention relates generally to ultrasonic transducers, and, more particularly, to a system for attaching the acoustic element of an ultrasonic transducer to an integrated circuit.
Ultrasonic transducers have been available for quite some time and are particularly useful for non-invasive medical diagnostic imaging. Ultrasonic transducers are typically formed of either piezoelectric elements or micro-machined ultrasonic transducer (MUT) elements. The piezoelectric elements typically are made of a piezoelectric ceramic such as lead zirconate titanate (commonly referred to as PZT), with a plurality of elements being arranged to form a transducer assembly. A MUT is formed using known semiconductor manufacturing techniques resulting in a capacitive ultrasonic transducer cell that comprises, in essence, a flexible membrane supported around its edges over a silicon substrate. By applying contact material, in the form of electrodes, to the membrane, or a portion of the membrane, and to the base of the cavity in the silicon substrate, and then by applying appropriate voltage signals to the electrodes, the MUT may be energized such that an appropriate ultrasonic wave is produced. Similarly, when electrically biased, the membrane of the MUT may be used to receive ultrasonic signals by capturing reflected ultrasonic energy and transforming that energy into movement of the electrically biased membrane, which then generates a receive signal
The transducer elements can be combined with control circuitry forming a transducer assembly, which is then further assembled into a housing possibly including additional control electronics, in the form of electronic circuit boards, the combination of which forms an ultrasonic probe. This ultrasonic probe, which may include various acoustic matching layers, backing layers, and dematching layers, may then be used to send and receive ultrasonic signals through body tissue.
In the past, joining an acoustic sensor, such as a piezoelectric ceramic transducer element or a MUT element, to the electrical control circuitry required the use of many individual wires to connect each element of the transducer array to the control circuitry. In the case of large transducer arrays having many hundreds or thousands of elements, large wiring harnesses were required. Unfortunately, a large wiring harness increases the bulk and cost of the ultrasonic probe. For ultrasonic probes designed to be used inside the human body, it is desirable to reduce the overall size of the ultrasonic probe and cable. One manner of reducing the size of the probe is to provide the transducer element control electronics on an integrated circuit (IC) assembly. An IC in proximity to the transducer array may be used to transmit and receive from many small transducer elements and may also be used to combine the signals, thereby reducing or eliminating the bulky and expensive cables that typically connect the ultrasonic probe elements to the control electronics.
Placing the transducer array over the IC results in greater packaging efficiency. Unfortunately, there is no convenient way to connect the piezoelectric ceramic or MUT transducer elements to the control electronics.
Therefore, it would be desirable to have a way in which to connect both the piezoelectric ceramic and MUT elements of an ultrasonic transducer array directly to an IC.
The invention is a system for attaching an acoustic element to an integrated circuit (IC). The system provides various ways to connect piezoelectric ceramic or MUT transducer elements to an IC, thus reducing the number of conductors required to connect each element of the transducer array to the IC by combining the signals in the IC. In another aspect of the invention, the transducer elements include an electrically conductive acoustic layer having a backing layer and/or a dematching layer that is connected to an IC.
Other systems, methods, features, and advantages of the invention will be or will become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present invention, and be protected by the accompanying claims.